text: /* Machine-dependent pthreads configuration and inline functions.
     i686 version.
     Copyright (C) 1996-2001, 2002 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Richard Henderson <rth@tamu.edu>.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public License as
     published by the Free Software Foundation; either version 2.1 of the
     License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; see the file COPYING.LIB.  If not,
     write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.  */
  
  #ifndef _PT_MACHINE_H
  #define _PT_MACHINE_H	1
  
  #ifndef PT_EI
  # define PT_EI extern inline
  #endif
  #include "kernel-features.h"
  
  #ifndef ASSEMBLER
  extern long int testandset (int *spinlock);
  extern int __compare_and_swap (long int *p, long int oldval, long int newval);
  
  /* Get some notion of the current stack.  Need not be exactly the top
     of the stack, just something somewhere in the current frame.  */
  #define CURRENT_STACK_FRAME  __builtin_frame_address (0)
  
  
  /* Spinlock implementation; required.  */
  PT_EI long int
  testandset (int *spinlock)
  {
    long int ret;
  
    __asm__ __volatile__ (
  	"xchgl %0, %1"
  	: "=r" (ret), "=m" (*spinlock)
  	: "0" (1), "m" (*spinlock)
  	: "memory");
  
    return ret;
  }
  
  
  /* Compare-and-swap for semaphores.  It's always available on i686.  */
  #define HAS_COMPARE_AND_SWAP
  
  PT_EI int
  __compare_and_swap (long int *p, long int oldval, long int newval)
  {
    char ret;
    long int readval;
  
    __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"
  			: "=q" (ret), "=m" (*p), "=a" (readval)
  			: "r" (newval), "m" (*p), "a" (oldval)
  			: "memory");
    return ret;
  }
  #endif
  
  #if __ASSUME_LDT_WORKS > 0
  #include "../useldt.h"
  #endif
  
  /* The P4 and above really want some help to prevent overheating.  */
  #define BUSY_WAIT_NOP	__asm__ ("rep; nop")
  
  #endif /* pt-machine.h */
  